HR: 11:25h
AN: P11C-05 INVITED     [PDF]
TI: The Power of JIMO for Determining Galilean Satellite Internal Structure and Origin
AU: * Stevenson, D J
EM: djs@gps.caltech.edu
AF: Caltech, 150-21, Pasadena, CA 91125
AU: McKinnon, W B
EM: mckinnon@levee.wustl.edu
AF: Washington University, Dept. Earth & Planetary Science, St. Louis, MO 63130
AU: Canup, R
EM: robin@boulder.swri.edu
AF: Southwest Research Institute, 1050 Walnut Street, Boulder, CO 80302
AU: Schubert, G
EM: schubert@ucla.edu
AF: UCLA, Dept. Earth & Space Sciences, Los Angeles, CA 90024
AU: Zuber, M
EM: zuber@mit.edu
AF: MIT, EAPS, Cambridge, MA 01239
AB: The spectacularly successful Galileo mission has opened up a planetary system (the Galilean satellites) for detailed exploration. The current state and origin of these bodies may tell us about many general aspects of the origin and evolution of planets as well as the processes that govern and structure in large icy (and rocky) bodies. JIMO offers the prospect of an enormous increase in our understanding in the following ways: (1) Determination of the global differentiation structure by characterizing the hydrostatic part of the gravity field (primarily J2 and C22) and the pole and thus spin obliquity. Although it is commonly supposed that Galileo gave us the correct moments of inertia, this is based on assumptions and could be wrong for Callisto especially. (2) Detection of oceans through the detection of eccentricity tidal response in both gravity and altimetry. Theoretical estimates indicate that the tidal response with and without an ocean are markedly different (especially for Europa) so this will be a very clear determination of ocean presence. (3) To the extent possible, the actual ice thickness will also be determined from tidal response. This is most important but also most difficult for Europa, because of our imperfect understanding of ice properties. The best prospect for success comes from the combination of many different kinds of measurements. (4) Orbital acceleration is detectable and will tell us about the tidal orbital evolution. (5) Magnetic field measurements will tell us about Ganymede's dynamo and the nature of Europa's ocean. (6) Non-hydrostatic gravity will tell us about the dynamic state of the rocky core and possibly the convective state of an ice shell. (7) Heat flow measurements are difficult but very valuable if possible. (8) Last but not least, all of these measurements will yield greatest return if they are in conjunction with probe measurements of Jupiter's deep atmospheric composition. This abstract has benefited form the entire JIMO Science Definition team and participants at the June workshop.
DE: 5430 Interiors (8147)
DE: 6218 Jovian satellites
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting